The present invention relates to a work vehicle such as an agricultural work vehicle, a transporter vehicle, a grass mower, a multi-purpose vehicle, including a traveling transmission line having a gear type auxiliary speed-change device disposed transmission-wise downstream of a hydrostatic continuously variable speed-change device (HTT).
A multi-purpose vehicle as an example of the above-described work vehicle is known from e.g. JP 2004-257447. In this, engine power is inputted to a main speed-change device (HST) to be speed-changed steplessly and this speed-changed output in a predetermined rotational direction is transmitted to a gear type auxiliary speed-change device which effects switchover between forward traveling and reverse traveling and effects also multi-stage speed changing operations in the forward traveling speed.
With the above-described transmission construction, when a switchover operation of the auxiliary speed-change device is to be effected, the speed-changing operation is effected with actuating a drivetrain brake. However, when e.g. an auxiliary speed-changing operation is to be effected during an upslope traveling, if there exists a significant pressure difference in the speed-changing oil passage of the HST, that is, if the gear shifting operation is to be effected while the auxiliary speed-change device is being subjected to the torque from the HST, the shifting operation cannot sometimes be effected smoothly, thus inviting great trouble of having to effect the speed-changing operations for a plurality of time in repetition.